I am new to Elasticsearch and Logstash, I want to know how Logstash can Sync data with Elasticsearch, for example, what mechanism does Logstash have to recognize a changed data field or just scan the entire database every time it is scheduled?
Hi @Coftbred,
Welcome! I assume you're specifically talking about the JDBC input plugin that can be used to ingest data from a database into Elasticsearch?
You'll see from the example in the documentation that you set a cron schedule to poll the database using the specified SQL statement. There's a bit of commentary on the state in there too, but you can also check out the code if you want to understand the nitty-gritty of the implementation.
Hope that helps!